Cutting Element For A Retracting Needle Syringe

ABSTRACT

A cutting element for a retracting needle syringe having a plunger with a cuttable distal end and a spring biased needle held by a cuttable support and a cutting element capable of cutting the cuttable distal end and the cuttable support includes a body portion having a proximal end, a distal end side wall therebetween and a passageway therethrough. The distal end of the body portion includes a cutting edge and a raised distally projecting tapered cutting tooth having distally converging edges. At least one tooth edge includes a sharp side wall for cutting the distal end of the plunger and the needle support.

This patent application is a continuation of pending U.S. applicationSer. No. 13/558,877, filed on Jul. 26, 2012, which is a continuation ofU.S. application Ser. No. 11/294,256, filed on Dec. 5, 2005, issued asU.S. Pat. No. 8,277,409, on Oct. 2, 2012, the entire contents of each ofwhich are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to syringes and needle assemblies. Moreparticularly, the present invention relates to a cutting element for asyringe and needle assembly having structure allowing for the withdrawalof the needle cannula into the syringe barrel after use.

BACKGROUND

In recent years there has developed an increased concern regarding thetransfer of disease, infection and the like to syringe users andhealthcare professionals who accidentally or through negligent handling,stick themselves with hypodermic needles while disposing of usedhypodermic needle. In many areas in a hospital, where needle cannulaproducts are used, disposal bins are provided so that a syringe or otherneedle cannula product may be immediately discarded in a safe rigidcontainer. However, there are areas of medical practice, such asemergency rooms, where disposal containers may not be readily availableor practical, and where products having self-contained safety featuresare desirable. In theory, after such a syringe is used to injectmedication or for another purpose, a safety device contained within thesyringe or needle assembly is activated to prevent further contact withthe sharp needle tip. One type of safety syringe includes structurewhich allows the withdrawal of the hypodermic needle into the syringebarrel to minimize the chance of further contact with the sharp needletip.

The prior art includes retracting needle syringes which include a springloaded needle assembly which is held in position during normal use ofthe syringe assembly and a hollow plunger rod which is sealed duringnormal use of the syringe assembly so that medication or other liquidsmay not enter the plunger rod cavity. These syringes must have structureto allow release of the spring-loaded needle and the opening of theplunger rod cavity so that the needle may enter the plunger rod cavityafter the syringe is used for its intended purpose. To functionproperly, the cavity in the plunger rod must be sealed so thatmedication cannot enter into the plunger rod during use. This seal mustsometimes withstand high hydraulic pressures when injecting relativelyviscous medication through small needles and still be capable of beingeasily unsealed and to allow access by the needle assembly. Likewise,the needle assembly must be firmly held in place through the forces ofinjection and still be disengageable so that it may retract into thesyringe barrel and into the plunger rod. Some of the prior artretracting needle syringes to solve these problems by providing aleak-proof physical structure for holding the spring-loaded needle inposition and for sealing the end of the hollow plunger rod. Uponcompletion of the injection process additional distally directed forceis applied to the plunger causing an internal cutting element to cutthrough the end of the hollow plunger rod and the support for thespring-loaded needle. In some embodiments, the prior art retractingneedle syringe cutter cuts in a proximal direction through the supportfor the spring-loaded needle assembly and then through the distal end ofthe plunger rod. In both cases this allows the spring-loaded needle toenter the cavity in the plunger helping to keep the user safe fromaccidental needle sticks.

Prior art retracting needle syringes that rely on dislodgeable elementsor the breaking of frangible barriers will allow the spring-loadedneedle to enter into the plunger can require a broad range of forces todisengage the spring-loaded needle. Retracting needle syringes with thecutter have an inherent advantage of being capable of being made so thatthe forces necessary to activate the retracting needle are moreconsistent from syringe to syringe.

The present invention addresses an improved cutting element for aretracting needle syringe for providing even more consistent syringe tosyringe activation forces and, if desired, lower activation forces.

SUMMARY OF THE INVENTION

A cutting element for a retracting needle syringe having a plunger witha cuttable distal end and a spring biased needle held in an energizedstate by a cuttable support is provided. The cutting element is capableof cutting the cuttable distal end of the plunger and the cuttablesupport. The cutting element includes a body portion having a proximalend, a distal end, a side wall therebetween defining a longitudinal axisand a passageway therethrough. The distal end of the body portionincludes a cutting edge and a raised distally projecting tapered toothhaving a distal tip and distally converging edges. At least one toothedge includes a sharp side for cutting the distal end of the plunger andthe support.

The sharp side wall may include a beveled edge. The cutting element mayinclude a plurality of cutting teeth which may or may not be equallyspaced around the distal end of the body portion. The distallyconverging edges of the cutting tooth may meet to form a distallydirected point or not meet and define a distally directed edge at thedistal tip.

The cutting element may be configured so that the cutting teeth includetwo sharp sides for cutting. The cutting teeth may be separated byconcave cutting edges running along the distal end of the body portion.

For cutting elements having two or more teeth, the cutting edges betweenthe cutting teeth may be about the same height when measured along thelongitudinal axis or the cutting edges may be at different heights whenmeasured along the longitudinal axis of the cutting element.

For cutting elements having two or more teeth, the distal tips of eachcutting tooth may be about the same height when measured along thelongitudinal axis or the distal tips may be at different heights whenmeasured along the longitudinal axis of the cutting element.

The body portion of the cutting element may be cylindrically shaped.Further, the cutting element configured so that it has three teeth orfour teeth.

The cutting element is desirably made of metal and preferably made ofstainless steel.

In another embodiment of the present invention the cutting element for aretracting needle syringe having a plunger with a cuttable distal endand a spring-biased needle held in an energized state by a cuttablesupport is provided. The cutting element is capable of cutting thecuttable distal end of the plunger and the cuttable support. The cuttingelement includes a cylindrically shaped sheet metal body portion has aproximal end, a distal end, a side wall therebetween defining alongitudinal axis and a passageway therethrough. The distal end of thebody portion includes a beveled cutting edge and at least three (3)distally projecting tapered cutting teeth having a distal tip anddistally converging beveled cutting edges meeting to form a distallydirected point at the distal tip for cutting. The beveled cutting edgeon the distal end of the body portion is concavely shaped in the spacesbetween the teeth which are substantially equally spaced around thedistal end of the body portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the retracting needle syringe.

FIG. 2 is an exploded perspective view of the retracting needle syringeof FIG. 1.

FIG. 3 is a cross-sectional view of the retracting needle syringe ofFIG. 1 taken along line 3-3.

FIG. 4 is an enlarged cross-sectional view of the outer hub of theretracting needle assembly.

FIG. 5 is an enlarged cross-sectional view of the inner hub of theretracting needle assembly.

FIG. 6 is an enlarged cross-sectional view of the retracting needleassembly.

FIG. 7 is an enlarged cross-sectional view of the distal end of thesyringe barrel.

FIG. 8 is a cross-sectional view of the distal end of the retractingneedle syringe of FIG. 1 illustrating the syringe after the liquidcontained therein has been delivered.

FIG. 9 illustrates the syringe of FIG. 8 when the proximal and distalportions of the plunger rod have separated and the cutting element hascut through the stopper and the inner hub.

FIG. 10 illustrates the syringe of FIG. 9 when the cutting element hascut completely through the inner hub and the needle has retracted intothe plunger.

FIG. 11 is a perspective view of a prior art cutting element forretracting needle syringe.

FIG. 12 is a side-elevational view of the cutting element of FIG. 11.

FIG. 13 is a side-elevational view of a cutting element of the presentinvention.

FIG. 14 is a perspective view of the distal end of the cutting elementof FIG. 13.

FIG. 15 is a perspective view of the distal end of a preferred cuttingelement for a retracting needle syringe of the present invention.

FIG. 16 is a perspective view of the distal end of an alternativecutting element of the present invention.

FIG. 17 is a perspective view of the distal end of another alternativecutting element of the present invention.

FIG. 18 is a side-elevational view of the distal end of still anotheralternative cutting element of the present invention.

FIG. 19 is a side-elevational view of the distal end of anotheralternative cutting element of the present invention.

DETAILED DESCRIPTION

While this invention is satisfied by embodiments in many differentforms, there are shown in the drawings and will herein be described indetail, preferred embodiments of the invention with the understandingthat the present disclosure is to be considered exemplary of theprinciples of the invention and not intended to limit the scope of theinvention to the embodiments illustrated. The scope of the inventionwill be measured by the appended claims and their equivalents.

Referring to FIGS. 1-17, an operable retracting needle syringe 20includes a retracting needle assembly 21, a syringe barrel 22 and aplunger 23. The barrel includes an inside surface 25 defining a chamber27, an open proximal end 28 and a distal end 29 including a cylindricalcollar 31 having an outside surface 32 and an inside surface 33.

The plunger is slidably positioned in fluid-tight engagement with theinside surface of the barrel. The plunger preferably includes a proximalportion 37 having a distal end 38 with an elongate cavity 39 therein.

A cutting element 43 is positioned at distal end 38 of the proximalportion of plunger 23. Cutting element 43 includes a body portion 44having a proximal end 45, a distal end 46, a side wall 47 therebetweendefining a longitudinal axis 49 and a passageway 50 therethrough. Distalend 44 includes a cutting edge 48 and at least one raised distallyprojecting tapered cutting tooth 51 having a distal tip 53 and distallyconverging edges 52. At least one tooth edge includes a sharp side wall55. The tooth cutting element is an important feature of the presentinvention which offers advantages over prior art cutting elements havinga planar cutting edge perpendicular or at an angle to the longitudinalaxis of the cutting element. This advantage will be discussed in moredetail hereinafter. As best illustrated in FIG. 13, the distal tip 53 ofeach of the cutting teeth is preferably about the same height whenmeasured along the longitudinal axis as indicated by the letter B.Further, cutting edges 48 may or may not be at the same height whenmeasured along the longitudinal axis. In this embodiment cutting edges48 are at substantially the same height, as indicated by the letter A,when measured along the longitudinal axis.

A hollow distal portion 65 of plunger 23 is releasably connected toproximal portion 37 and capable of telescopic motion with respect to theproximal portion. A cover element on the distal portion seals a distalend 67. In this embodiment the cover element is stopper 70. It ispreferred that the cover element be made of an elastomeric materialselected from the group of thermoplastic elastomers, natural rubber,synthetic rubber and combinations thereof. The cover element can also bethermoplastic or a combination of thermoplastic support material andelastomeric material.

Retracting needle assembly 21 includes an outer hub 71 having a proximalend 73, a distal end 74 and a passageway 75 therethrough. The retractingneedle assembly also includes an inner hub 76 having a proximal end 77,a distal end 79 and a conduit therethrough 80. The inner hub includes aninner portion 81 and a cuttable outer portion 82 connected to the innerportion. The cuttable outer portion of the inner hub is connected toouter hub 71. Distal end 79 of the inner hub is smaller than passageway75 of the outer hub at distal end 74 and is accessible therefrom andpreferably projects distally outwardly therefrom.

A needle cannula 83 having a distal end 85, a proximal end 86 and alumen 87 therethrough. The proximal end of the cannula is connected todistal end 79 of the inner hub so that the lumen is in fluidcommunication with conduit 80 of the inner hub. The distal end of thecannula preferably includes a sharp or sharpened distal tip.

An energized spring is contained between the outer and inner hubs andthis preferred embodiment the energized spring is a compressed coilspring 88. Various spring types and elastomeric materials and the likecan be used to provide a biasing force between the inner and outer hubswith the coil spring being merely representative of these manypossibilities all of which are within the purview of the presentinvention. A coil spring is preferred because of its compact size andthe ability to easily design the spring to provide the forces necessaryfor proper operation of the retractable needle assembly.

During assembly the coil spring is placed over the inner portion of theinner hub and then the distal end of the spring is positioned in theouter hub and the inner and outer hubs are moved toward each other tocompress the spring and lock together through the action of annularlocking projection 78 on the inner hub and annular locking recess 72 inthe outer hub. When the inner hub and outer hub are joined, compressingthe coil spring, annular locking projection on the inner hub snaps intoannular locking recess 72 in the outer hub. The projection and therecess are shaped so that much less force is required to assemble thecomponents than to reverse the process, thus providing for a permanentlocked condition wherein the inner hub and the outer hub are inseparableduring normal operating conditions. There are numerous ways to connectthe inner and outer hub and the snap-fit arrangement taught herein ismerely representative of all of these methods which are within thepurview of the present invention. In particular, adhesives, separatemetal locking clips, ultrasonic welding, crimping, internally moldedlocking structure and the like can be used to hold the inner hub and theouter hub together.

A preferred way to connect the needle cannula to the retracting needleassembly is to place the proximal end of the needle cannula into thedistal end of conduit 80 of the inner hub. An enlarged or irregularportion 84 at the distal end of conduit 80 provides a space for adhesive89 to be placed around the outside of the needle cannula after it ispositioned in the conduit.

The retracting needle assembly also includes means for connecting theouter hub to the collar of the syringe barrel. In this embodiment, meansfor connecting includes structure providing for threadable engagementbetween the collar and the outer hub. In this preferred embodiment thestructure for threadable engagement includes at least one thread 90 inpassageway 75 of outer hub 71 and at least one thread 34 on outsidesurface 32 of the cylindrical collar. Thus the needle assembly, in thisembodiment, is removably connected to the barrel. This feature allowsflexibility to interchange needle assemblies and syringes to obtain anappropriately sized needle and syringe combination for the desired drugtype and injection site. In addition, the structure of this embodimentallows the installation and removal of the needle assembly from thebarrel using the same motions required for installation and removal of astandard hypodermic needle from a standard hypodermic syringe so that noadditional training is required for the health care worker.

The structure for threadable engagement between the collar and the outerhub can include a wide variety of thread-like and bayonette-typestructures including a thread on the outside surface of the collar and athread follower projection on the inside surface of the outer hub whichwill follow the collar thread as the hub is screwed onto the collar.This structure is similar to the well-known locking luer-type needleassembly and syringe combinations wherein the syringe collar has athread on its inside surface and the needle assembly has two outwardlydirected projections on the base of its hub for allowing the hub followthe threads of the collar as it is screwed onto the luer tip and collar.Also, the inside of the collar can be threaded in the outside of theouter hub can have thread followers.

It is also within the purview of the present embodiment to include meansfor connecting the outer hub to the collar which is permanent ratherthan removably engageable. For example, the outer hub can be attached tothe collar using adhesive or ultrasonic welding, retaining clips or aone-way snap-fit arrangement that renders the assembly irreversibleunder normal use. Such structures fall within the purview of the preventinvention.

It should be noted that the needle assembly need not be removable orseparate from the barrel. Elements of the barrel and the needle assemblycan be optimized to reduce the number of parts and achieve a permanentlyattached needle assembly.

To help prevent leakage, this embodiment includes tapered cylindricalsurface 91 on inner hub 76 and tapered cylindrical surface 35 on theinside of cylindrical collar 31 of the barrel. When the retractingneedle assembly engages the collar of the barrel, the taperedcylindrical surface 35 on the collar engages tapered cylindrical surface69 on the inner hub to seal the interface between the hub and the collarto prevent leakage during normal use. A gasket may also be used to sealsome portion of the contact surfaces between the needle assembly and thebarrel.

In use, the retracting needle assembly of the present invention can beremovably connected to syringe barrel 22 containing plunger 23. A needleshield 93 can now be removed from the retracting needle assembly thusexposing the needle cannula for use. The retracting needle syringe canbe filled, using known methods for such uses as withdrawing injectableliquid from a vial having a pierceable stopper. A syringe may then beused to inject liquid into a patient, an I.V. set, a catheter or othersuitable device. After the liquid in the chamber is injected orotherwise delivered, the distal end of the stopper will be contactingthe distal end of the barrel chamber as best illustrated in FIG. 8. Atthis point, the user can apply additional distally directed axial forceto the proximal end of the plunger through proximal flange 41 to bottomout the stopper on the distal end of the barrel chamber and to cause thedisengagement of the proximal portion 37 of the plunger from distalportion 65 of the plunger. Because the connection between the proximalportion of the plunger and the distal portion of the plunger is brokenor overcome, the proximal portion will move distally within the distalportion and along the barrel advancing cutting element 43 so that itssharp distal end will press on and cut through stopper 70 and throughthe inner hub between inner portion 81 and cuttable outer portion 82, asbest illustrated in FIG. 9. Application of a distally directed force tothe plunger which causes the release element to cut completely throughthe inner hub, will allow the spring to propel the inner portion of theinner hub along with the needle cannula into the elongate cavity of theplunger as best illustrated in FIG. 10. The used needle cannula is nowsafely contained within the syringe assembly and ready for safedisposal.

In this embodiment the releasable connection between proximal portion 37of the plunger and distal portion 65 of the plunger which allows thetelescopic relative motion between the two plunger portions is providedby a snap-fit arrangement between the proximal portion of the plungerand the distal portion of the plunger. In particular, an annularprojection 68 on the inside of the proximal end of the distal portion 65of the plunger engages an annular groove 40 on the proximal end ofproximal portion 37 of the plunger. When sufficient axial force isapplied, annular projection 68 disengages from annular groove 40allowing the distal end of the release element to cut through thestopper and the inner hub between the cuttable outer portion and theinner portion. There are numerous structures and materials and elementswhich can provide for a releasable connection between the proximal anddistal portions of the plunger with the structure taught hereinabovebeing merely representative of the many possibilities all of which arewithin the purview of the present invention. In particular, anycombination of projections and/or recesses and/or discontinuities on theproximal portion and the distal portion can accomplish a similar result.Also, the connection can also be breakable as well as disengageable suchas by use of a frangible adhesive between the two elements or moldingthe elements as an integral structure containing a brittle plasticprojection or projections which join the elements and can be broken witha force applied to the plunger. A breakable connection can also be madeby connecting the elements with a sheer pin. A sheer pin made be made ofplastic with one or more notches or stress risers suitably placed tocause breaking at the desired force levels. A breakable connection mayalso be accomplished similar to the snap fit arrangement but designingthe various projections and recesses to fail upon reaching the desiredstress level. Also, it should be noted that a one-piece plunger ispossible if the stopper is designed to deflect into a fixed cuttingelement when excess force is applied to the plunger.

A prior art cutting element 143 is illustrated in FIGS. 11 and 12. Thecutting element includes a proximal end 145, a distal end 146 and a sidewall 147 therebetween. Distal end 146 further includes a cutting edge148. Prior art cutting elements are essentially cylindrical in formhaving a circular and planar cutting edge. The cutting edge is typicallyperpendicular to the longitudinal axis of the cutting element so thatthe cutting element's first contact is the inner surface of the stopper,or needle supporting element, depending on the design, is a fullcircular contact. When pressing against the stopper's interface thecutting mechanism is one of “chopping” wherein the cutter's circularedge penetrates directly into the stopper's inner surface. There is nosliding component to the cut. This type of action requires a very sharpedge so that the load required to make the cut is minimized. A sheetmetal cutting element, depending on the manufacturing process used inits formation can be reasonably sharp as made. However, a post-formingsharpening process is required. Further, the cutter is hardened so thatthe very fine edge does not deform during the cutting process. Contactcutters tend to experience a wider range of cutting forces possiblyassociated with dimensional and material variations and cutter elementsharpness. Forming the planar cutting edge at angle with respect to thelongitudinal axis can reduce the chopping component of the cuttingforce.

The cutting element of the present invention offers a more robust designthat does not necessarily require heat treatment or post-formingsharpening operations and reduces potential for having wide variationsof forces required to achieve cutting of the stopper and the needlesupport structure. The cutting mechanism of the cutting element of thepresent invention is not primarily “chopping” but rather one of“piercing and shearing.” The cutting edge geometry of the cuttingelement of the present invention is not a circular plane but ratherpointed crown geometry. By changing the mechanism by which the cutteroperates, the cutting force is reduced and so is the need forpost-formation sharpening and heat treating.

FIG. 15 illustrates the distal end of a preferred cutting element 243 ofthe present invention. Cutting element 243 includes a body portion 244having a distal end 246 and a generally cylindrical side wall 247defining a passageway 250 therethrough. The distal end includes cuttingedge 248 and three distally projecting tapered cutting teeth 251 havingdistally converging edges 252. In this embodiment all three cuttingteeth have a sharp side wall in the form of beveled edges 257. Eachcutting tooth includes a distally directed point 258. The cutting teethin this embodiment are substantially equally spaced around the distalend of the body portion and are separated by concave cutting edges 261,i.e., the cutting edge is concavely shaped in the spaces between thecutting teeth.

The pointed geometry of the teeth together with chiseled point profileof each of the points creates an initial contact against the targetsurface with very low surface area. When a force is applied, the loaddivided by the surface area defines the stress of penetration. Since thesurface area is close to zero, the penetration stress is very high andcapable of penetrating a target with only a very small load relative toprior art cutting elements. Once the penetration is established, thesharp beveled edges of the cutting teeth slice the target materialrather than chop it. The applied forces is therefore administered over alonger distance along the longitudinal axis, thus requiring less forcefor equivalent work performed. Near the end of the cut, the targetmaterial is gathered between the roots of the cutting teeth, and thefinal portion of the cutting action indeed becomes a “chop,” but theamount of material remaining is relatively small so that the forcerequired to complete the cut is minimized.

The cutting element of the present invention can be tuned to provide anumber of different feels while cutting based on the number of cuttingteeth, the depth, the teeth, the form of the points, the form of theroots between the teeth and by formation of a chisel edge upon theprofile of each cutting tooth. Based on these variations, a very softfeel, a very hard feel or countless interim feels can be produced.

FIG. 16 illustrates an alternative cutting element of the presentinvention. In this embodiment cutting element 343 includes a bodyportion 344 having a distal end 346 and a generally cylindrical sidewall 347 defining a passageway 350 therethrough. The distal end includescutting edge 348 and four distally projecting tapered cutting teeth 351having distally converging edges 352. In this embodiment all fourcutting teeth have a sharp side wall in the form of beveled edges 357.Each cutting tooth includes a distally directed point 358. The cuttingteeth in this embodiment are substantially equally spaced around thedistal end of the body portion and are separated by concave cuttingedges 361, i.e., the cutting edge is concavely shaped in the spacesbetween the cutting teeth.

FIG. 17 illustrates another alternative embodiment of the presentinvention. In this embodiment, cutting element 443 includes a distal end446, a side wall 447 and a passageway 450 through the cutting element.The cutting element in this embodiment includes six raised distallyprojecting tapered cutting teeth 451 having distally converging edges452 terminating at a distally directed cutting edge 459. In thisembodiment, all six cutting tooth edges have sharp side walls in theform of beveled edges 457. Distally directed cutting edge 459 alsopreferably includes a beveled cutting surface 463. The distally directedcutting edge may be desirable over a cutting point in situations wherethe force required to initiate cutting is desired to be higher than thatpossible with the pointed cutting tooth.

As indicated hereinabove, near the end of the cut, the target materialcontacts the cutting edges between the cutting teeth wherein the finalportion of the cutting action becomes a “chop”. The amount of materialremaining is relatively small so that the force required to complete thecut is minimized. The force is minimized even further by having theconcave cutting edges which further reduce the amount of material thatmust be cut using a chopping action. The force of this final choppingaction can also be reduced by staggering the cutting edges asillustrated in the embodiment of FIG. 18. In this embodiment, cuttingelement 543 includes a distal end 546, a side wall 547 and a passagewaytherethrough. The cutting element in this embodiment includes six raiseddistally projecting tapered cutting teeth 551 having distally convergingedges 552 terminating at a distal tip 553. The cutting teeth in thisembodiment are substantially equally spaced around the distal end of thebody portion and are separated by concave cutting edges 561. At leasttwo of the cutting edges between the cutting teeth are at differentheights when measured along the longitudinal axis of the cuttingelement. In this embodiment, at least one cutting edge is positioned atdistance C, measured along the longitudinal axis, while at least oneother cutting edge is positioned at a different distance D, whenmeasured along the longitudinal axis. Accordingly, the final minimalchopping action of the cutter is staggered to reduce the cutting forcerequired. In this embodiment, every other cutting edge is at distance Cand those cutting edges in between are at distance D.

FIG. 19 illustrates another alternative embodiment of the presentinvention. This embodiment is similar to the embodiment of FIG. 18except that the force required for the initial cutting action is reducedby staggering the distal tips of the cutting teeth. In this embodiment,cutting element 643 includes a distal end 646, a side wall 647 and apassageway therethrough. A cutting element in this embodiment includessix raised distally projecting tapered cutting teeth 651 having distallyconverging edges 652 terminating at distally directed point 658 at thedistal tip. The cutting teeth in this embodiment are substantiallyequally spaced around the distal end of the body portion and areseparated by concave cutting edges 661. At least two of the cuttingedges between the cutting teeth are at different heights when measuredalong longitudinal axis 649 of the cutting element. In this embodiment,at least one cutting edge is positioned at distance E, measured alongthe longitudinal axis, while at least one other cutting edge ispositioned at a different distance F, when measured along thelongitudinal axis. Also, at least two of the distally directed points558 are at different heights when measured along the longitudinal axisof the cutting element. In this embodiment, at least one distallydirected point is positioned at distance H, measured along thelongitudinal axis, while at least one other cutting edge is positionedat a different distance J, when measured along the longitudinal axis.Accordingly, staggering of the distally directed points 658 reduces thecutting force during this phase of cutting by not having all cuttingaction starting simultaneously.

It is desirable to make the cutting element out of metal such as sheetmetal and preferably of stainless steel. However, any material suitablefor cutting through the syringe components in question may be used toform the cutting element, such as plastic materials, ceramics and thelike, all of which are within the purview of the present invention. Thecutting element in the preferred embodiments for the present inventionhas a cylindrical side wall, however other shapes such as elliptical ormulti-sides, such as hexagonal, square and the like are within thepurview of the present invention and the cylindrical body portionillustrated is merely representative of these many possibilities.

Other retracting needle syringes such as retracting needle syringetaught in U.S. Pat. No. 6,432,087 B1 operate in a similar manner to theretracting needle syringe herein described but contain the cuttingelement in the distal end of the syringe barrel with the cutting edgefacing in a proximal direction. In this type of retracting needlesyringe, after the injection, the user provides an additional distallydirected force to the plunger which causes the cutting element to cutthrough the support structure holding the energized spring and theneedle and then through the distal end of the plunger to allow thespring to move the needle into the plunger cavity. The present cuttingelement is also intended to work in syringes of this type.

What is claimed is:
 1. A retracting needle syringe comprising a) asyringe barrel including an inside surface defining a chamber, an openproximal end and a distal end including a cylindrical collar having anoutside surface and an inside surface; b) a plunger slidably positionedin fluid-tight engagement with the inside surface of the barrel, theplunger comprising (i) a proximal portion having an elongate cavitytherein, a distal end, and a cutting element positioned at the distalend, wherein the cutting element comprises a body portion having aproximal end, a distal end, a side wall therebetween defining alongitudinal axis and a passageway therethrough, the distal endincluding a cutting edge and a plurality of raised distally projectingtapered cutting teeth each having a distal tip and distally convergingedges, at least one tooth edge having a sharp side wall for cutting astopper on a distal end of a hollow distal portion of the plunger,wherein the cutting teeth are separated by curved concave cutting edgesrunning along the distal end of the body portion, (ii) a hollow distalportion having the proximal portion inserted therein, wherein the distalportion is releasably connected to the proximal portion and capable oftelescopic motion with respect to the proximal portion upon release ofthe releasable connection, and (iii) a stopper on the distal end of thehollow distal portion which seals the distal end of the distal portion,wherein the stopper is made of an elastomeric or thermoplastic material;c) a retracting needle assembly connected to the barrel, the retractingneedle assembly comprising (i) an outer hub having a proximal end, adistal end and a passageway therethrough, (ii) an inner hub having aproximal end, a distal end and a conduit therethrough, and including aninner portion and a cuttable outer portion connected to the innerportion, wherein the cuttable outer portion of the inner hub isconnected to the outer hub and the distal end of the inner hub issmaller than the passageway of the outer hub at the distal end of theouter hub, and (iii) an energized spring contained between the outer andinner hubs of the retracting needle assembly.
 2. The retracting needlesyringe of claim 1, further comprising a needle cannula having a lumentherethrough and a proximal end connected to the distal end of the innerhub so that the lumen is in fluid communication with the conduit of theinner hub.
 3. The retracting needle syringe of claim 1, wherein theenergized spring is a compressed coil spring.
 4. The retracting needlesyringe of claim 1, wherein the inner hub and the outer hub areconnected in a snap-fit arrangement
 5. The retracting needle syringe ofclaim 1, wherein the retracting needle assembly is connected to thebarrel by threadable engagement or by bayonette-type structures
 6. Theretracting needle syringe of claim 1, wherein the retracting needleassembly is removably connected to the barrel.
 7. The retracting needlesyringe of claim 1, wherein the releasable connection between theproximal portion and distal portion of the plunger is a snap-fitconnection between the proximal portion and the distal portion.
 8. Theretracting needle syringe of claim 7, wherein the snap-fit connectioncomprises an annular projection on the inside of the proximal end of thedistal portion of the plunger which engages an annular groove on theproximal end of the proximal portion of the plunger.
 9. The retractingneedle syringe of claim 1, wherein the releasable connection is a shearpin.
 10. The retracting needle syringe of claim 1, wherein the sharpside wall of the tooth edge includes a beveled edge.
 11. The retractingneedle syringe of claim 1, wherein the distal tip of each of the cuttingteeth is at about the same height when measured along the longitudinalaxis.
 12. The retracting needle syringe of claim 1, wherein at least twoof the distal tips of the cutting teeth are at different heights whenmeasured along the longitudinal axis.
 13. The retracting needle syringeof claim 1, wherein at least two of the curved concave cutting edgesseparating the cutting teeth are at different heights when measuredalong the longitudinal axis.
 14. The retracting needle syringe of claim1, wherein at least two of thed distal tips of the cutting teeth are atdifferent heights when measured along the longitudinal axis and at leasttwo of the curved concave cutting edges separating the cutting teeth areat different heights when measured along thed longitudinal axis.
 15. Theretracting needle syringe of claim 1, wherein thed plurality of cuttingteeth are substantially equally spaced around the distal end of the bodyportion.
 16. The retracting needle syringe of claim 1, wherein thecurved concave cutting edges include a beveled edge.
 17. The retractingneedle syringe of claim 1, wherein both edges of the teeth have a sharpside for cutting.
 18. The retracting needle syringe of claim 1, whereinthe body portion is cylindrically shaped.
 19. The retracting needlesyringe of claim 1, wherein the plurality of cutting teeth comprisesthree (3) cutting teeth or four (4) cutting teeth.
 20. The retractingneedle syringe of claim 1, wherein the body portion of the cuttingelement is made of metal.